Table Grapes: There Is More to Vitiviniculture than Wine…

*Ana Cristina Agulheiro-Santos, Marta Laranjo and Sara Ricardo-Rodrigues*

### **Abstract**

Table grapes are fruits intended for fresh human consumption due to their sensory attributes and nutritional value. The objective of this chapter is to review the existing knowledge about table grapes, including a description of different varieties, with particular emphasis on the new highly appreciated seedless varieties. Following an introductory note on the world distribution and production of table grapes, also considering the impact of climate change, selected varieties of table grapes will be characterized in terms of their physiology, postharvest features, and consumer preferences. A morphological description of each variety, with emphasis on grape skin, grape rachis and grape cluster will be included. A final note on the drying of table grapes into raisins, and the most appropriate varieties for drying, will be given. The major changes occurring throughout the growth, development, and ripening phases of table grapes production will be discussed, regarding both physical (skin color and skin and pulp texture) and chemical (phenolic compounds, sugar content and acidity) parameters, as well as growth regulators.

**Keywords:** grapes, varieties, seedless, raisins, quality, consumer

### **1. Introduction**

Table grapes are destined for fresh human consumption because of their sensory, nutritional, and commercial attributes, which is in line with the definition adopted for table grapes by the *International Organization of Vine and Wine* [1] "A fresh grape, produced from special vine varieties or vine varieties cultivated for this purpose and destined for consumption as such, basically because of its sensory and commercial characteristics."

The consumption of the grapes can be fresh, or derived products such as juices, wines, raisins, and has increased due to the identification of beneficial compounds for human health in its constitution [2].

The culture of the vine is one of the most important agricultural crops in the world. The world production of grapes intended for all uses, in 2018, was 77.8 million tons, 57% wine grapes, 36% table grapes and 7% dried grapes [3]. In 2018 the world production of table grapes was 27.3 million tons (**Figure 1**).

In 2020, the world area planted with vines for all purposes, wine, juices, table grapes and raisins, is estimated at 7.3 million hectares. An apparent stabilization hides the reduction in the vineyard surface in Iran, Turkey, Portugal, Uzbekistan, and USA. The leading countries in 2020, were Spain, France, China, and Italy, respectively with 13.1%, 10.9%, 10.7%, 9.8% of vineyard surface area (**Figure 2**) [4].

**Figure 1.** *Major producer countries by type of grape in 2018 [3].*

The world consumption of table grapes has increased in recent decades, and there has been an increase in consumer demand for high quality table grapes [5]. According to the *International Organization of Vine and Wine* (OIV) in the beginning of this century, a continuous growth of areas under table grape production was observed until 2017. Between 2007 and 2009 there was a notable growth trend in the production of grapes for fresh consumption, of about 10% (**Figure 3**) [5].

A more detailed analysis of the world table grape production, considering the 2018/2014 ratio, shows an overall value of 2% and allows us to verify that Latin American countries like Peru and Mexico show an important production increase (respectively 0.8% and 0.5%) and Uzbekistan, USA, Brazil, South Africa, Greece, Spain, and Australia show more modest increments between 0.1 and 0.3%. In contrast, Turkey and India show even slight decreases in production [4]. In 2019, Europe produced 1.7 million tons of table grapes for fresh consumption, and ten years ago the production was more than 2.0 million tons (https://www.cbi.eu/ market-information/fresh-fruit-vegetables/table-grapes/market-potential).

In the year 2018, China was outstanding as the world's leading table grape producer, producing 9.5 million tons of grapes. The second ones were Turkey and India producing 1.9 million tons each, as it can be appreciated a much lower value.

*Table Grapes: There Is More to Vitiviniculture than Wine… DOI: http://dx.doi.org/10.5772/intechopen.99986*

#### **Figure 3.**

*World table grapes production from 2000 to 2018 in million tons [3].*

#### **Figure 4.**

*European imports of table grapes from non-European suppliers (https://www.cbi.eu/market-information/ fresh-fruit-vegetables/table-grapes/market-potential).*

Another important observation is the increasing exportation of fresh grapes from Chile, Peru, and Turkey, developing countries and new producers. Chilean season starts in December until April, and the USA, China, Netherlands, UK, Korea are main markets for Chilean grapes due to the cycle opposite to that of the Northern Hemisphere.

The import volume of table grapes from non-European suppliers has gradually increased from 602,000 to 694,000 tonnes between 2015 and 2019, corresponding to a value of 1.4 billion Euros in 2019 (**Figure 4**).

The main grape producing countries worldwide are Italy, France, USA, Spain, and China. The more non-European significant grape exporters in the international market were Chile, and USA and in Europe, Italy. On the other side, in 2018, only three countries in Europe imported 25% of the grapes traded globally, namely United Kingdom, Germany, and Netherlands.

The existence of market strategies can be perceived as the introduction of new varieties to different products, a goal to be reached by producers, mainly important producers and companies that are gaining prominence in the international market. Big grape companies are anticipating consumer preferences of seedless grapes and sustainable packaging, for large markets, such as the United Kingdom and Germany.

The crisis caused by the Covid-19 pandemics, turned 2020 into an abnormal year, regarding international trade, and dramatically decreased the demand for table grapes in the supermarkets, for example in Germany and in the UK. This crisis serves to test the resilience of the sector and to be expecting new opportunities in the value chain [6].

The *International Organization of Vine and Wine* is committed to achieve excellence towards environmental sustainability objectives on socio-economic and socio-cultural aspects, in support of the United Nations (UN) 2030 Sustainable Development Goals (SDGs) [4]. In their Strategic Plan 2020–2024, the *International Organization of Vine and Wine*, among the various proposed axes, highlighted the first three:

Axis I - Promote environmentally friendly viticulture, facing climate change through mitigation and adaptation activities.

Axis II - Promote economic activity in accordance with the principles of sustainable development and growth and globalization of markets.

Axis III - Contribute to social development through vitiviniculture.

In the 2020/2021 season, the global production of table grapes is estimated to be maintained at 25.7 million tons, although production in key productive regions, such as Chile, Europe, and the United States substantially decreased, mainly due to the increased production in China [7].

#### **2. Grapevine: family, genus, species, and varieties**

Grapevine is a hardy perennial plant, which belongs to the family *Vitaceae*. The plant is a climber with an herbaceous or twining stem, sometimes with tuberous stems, characterized by tendrils and inflorescences opposite the leaves [8, 9]. It bears fruit in clusters, and the fruit, grapes, is botanically called a berry that results from the development of the ovary of the flower [10].

The genus *Vitis* is the most representative of this family and the most interesting for the vine industry. It has over 80 identified species and is composed of two subgenera, *Muscadinia* (2n = 40 chromosomes) and *Euvitis* (2n = 38 chromosomes) [8, 10, 11]. The subgenus *Muscadinia* consists of three species, including *M. rotundifolia*, and is known by resistance to cryptogamic diseases.

The subgenus *Euvitis*, which is divided into three groups: (a) East Asia group consists of about 55 species and shows minor interest in present viticulture; (b) American group consisting of more than 20 species, including *V. labrusca*, *V. riparia* and *V. rupestris*, and shows high interest in use as a rootstock due to resistance to phylloxera; (c) Eurasian group composed of the species *Vitis vinifera* L., the most representative and planted worldwide. It consists of two sub-species: *sylvestris*, which corresponds to the wild form of the vine, and *vinifera*, the cultivated form [8, 11]. According to Creasy and Creasy [8], many of the non-*V. vinifera* species have been vitally important to the commercial development of *V. vinifera* cultivars, in finding a solution to the problem of phylloxera and other soil-related pests and conditions.

Nowadays, the genus *Vitis* presents a large genetic diversity with several thousands of varieties. However, there is a high number of synonyms (different names for the same cultivar) and homonyms (identical name for different cultivars) to be considered. Also, the number of varieties in the world is estimated at 6,000 for the *V. vinifera* species on its own [11]. Additional information on the origin, main use and pedigree of cultivars is available from the *Vitis International Variety Catalog* [12], which allows the rapid and easy comparison between molecular fingerprints.

The existing grape varieties have different features, regarding shape and size of the berry and bunch, berry tonality, organoleptic quality, productivity, among others, which give them aptitude for different uses.

*Table Grapes: There Is More to Vitiviniculture than Wine… DOI: http://dx.doi.org/10.5772/intechopen.99986*

Grapes can be considered for different uses according to their characteristics: (a) wine production and fermented grape products using varieties with higher acidity and moderate sugar content, (b) table grapes for fresh consumption, using varieties with low acidity, low in sugar and that meet specific standards of size, color and shape and (c) raisins, suitable varieties being seedless, with low acidity and rich in sugars [13].

According to recent data presented in the *Vitis* International Variety Catalog-VIVC [12], 53.98% of grape cultivars are used for wine production, 30.57% for table grapes (fresh consumption), 7.42% with dual suitability (wine and fresh consumption), 7.06% for rootstocks and less than 1%, more precisely 0.98% for raisins.

In table grape cultivars, berry size, firmness, sweetness, and color are important characteristics [14]. Berry size and yield are desirable in table grape vineyards, for which full irrigation is recommended [15].

However, some trials conducted by Shahidian and colleagues [16], in a vineyard of 'Crimson', with different irrigation sub-treatments with stress periods, showed significant decrease in mean berry weight, and thus in marketable fruit and also reduction in total soluble solids and an increase titratable acidity (TA), so the consequences of this stress period were a reduction in the maturity index and a delay in the maturity. The use of sap flow ratio between well irrigated reference vines and vines under reduced irrigation can potentially contribute to water savings, in order to find the level of irrigation reduction at non-critical stages of vine growth, triggering irrigation events only at a previously defined critical threshold.

The quality parameters of table grapes differ from wine berries quality parameters, and therefore irrigation practices to optimize berry quality can be quite different [17].

In wine vineyards, full irrigation is not recommended because it increases the size of the berries, which produces a decrease in the proportion of pulp in the skin, which does not benefit the quality of the wine.

Not be forgotten the use of rootstocks in grape plantation, that has become a common practice among grape growers around the world, mainly because rootstocks allow the culture to be conducted under unfavorable soil conditions, such as the presence of nematodes, diseases and pests, high salinity, among others [18, 19]. Around the world, most vineyards are grafted onto commercial hybrid rootstocks from *Vitis berlandieri*, *V. riparia*, or *V. rupestris,* which were developed at the beginning of the 20th century to control *Phylloxera* devastated European vineyards from American *Vitis* spp. [8]. The role of rootstocks in the maintenance of the crop and in the final product obtained has been studied given its relevance, particularly in aspects related to the symbiont's use of soil nutrients [20].

## **3. Description of the most important commercial varieties**

In the last decades, the cultivation of seedless table grape cultivars has increased considerably, because consumers in many countries highly appreciate these new varieties, seedless, with firm and sweet berries [21]. However, those who think that these seedless table grapes are new are mistaken, because as early as the 19th century, William Thompson in California achieved the first significant crop, 50 pounds of seedless grapes. This breeding work has relied on varieties from Turkey and local rootstocks.

The production of seedless, i.e., apyrenic, table grape varieties has been of increasing interest, mainly because the demand in recent decades has grown, since this type of fruit is more convenient to consume [21, 22]. In addition, the selling price of these varieties is usually higher than that of seeded grapes. So, many of the new table grape varieties that have recently come onto the market are apyrenic, and more appreciated and sought after by consumers.

In the case of seedless grapes, it is possible to distinguish two mechanisms of seedlessness depending on the time when development was disrupted: (a) parthenocarpy (observed in Corinth cultivars), which occurs when the ovary is able to develop without fertilization of the ovum; (b) stenospermocarpy (observed in Thompson cultivars), when pollination and fertilization trigger ovary development, but embryo/ovule abortion occurs 2 to 4 weeks after fertilization, and partially developed seeds or traces of seed are visible in the grape [23–25]. In seeded grapes, the transition from flower to fruit requires pollination and fertilization of the ovary for seed formation [23].

According to Costenaro-da-Silva et al. [26] and Varoquaux et al. [25] the parthenocarpy mechanism leads to the development of very small seedless and spherical berries that are usually considered for raisin production, while stenospermocarpy leads to the development of berries with dimensions compatible with commercial requirements for fresh consumption.

According to Picarella and Mazzucato [24] the term parthenocarpy is used in the broad sense to indicate both forms of apyrenia.

However, to obtain a bunch of grapes with a considerable number of well-developed berries, it is necessary to apply particular and complex hormonal treatments. Gibberellic acid is used to thin the bunch berries, elongate the bunch, increase berry size, and reduce seed traces. The concentration of the initial spray of gibberellic acid depends on the cultivar [25].

Seedlessness can also be induced by applying hormones to young inflorescences [24].

The shelf-life of seedless fruits is expected to be longer than seeded fruits, since seeds produce hormones that activate senescence [25].

#### **3.1 Seeded varieties**

#### *3.1.1 'Red globe'*

The bunches are pyramid-shaped, conical, with wings, semicircular. They can reach exceptionally large dimensions and weight. Berries are seeded large and spherical (9–10 g), consistent, the skin can be easily peeled, with a physical resistance worth mentioning that allow easy management and contribute to a long shelf-life. 'Red Globe' grapes are very sweet with a high soluble solids content (SSC) (19°Brix) and an SSC/TA ratio of 49, which makes them highly appreciated by consumers [27]. They also have a high resistance to rupture in compression, which makes them particularly interesting for postharvest handling and transport [27]. It is an early-budding variety with a long and late maturity period and a long shelf-life.

This variety is the second most cultivated variety for table grapes, covers 159,000 hectares worldwide, and 91% of the area under this variety is in China. 'Red Globe' yields between 8 and 30 tons per hectare [11].

#### *3.1.2 'Cardinal'*

'Cardinal' berries are large, spherical with a bright green color and a crisp flesh. They present a slight muscat flavor when fully ripe. This variety was introduced in Europe after the Second World War, and it is very important in the Mediterranean region. Preliminary results obtained with 'Cardinal' grapes grown in the south of Portugal have 17.5°Brix, an acidity of 0.43 g/100 g−1 fresh weight, and an SSC/TA ratio of 45 [27].

*Table Grapes: There Is More to Vitiviniculture than Wine… DOI: http://dx.doi.org/10.5772/intechopen.99986*

#### *3.1.3 'Italy'*

The berries are large, oval, with a crunchy texture, juicy, sweet, and present a very yellow color. The bunches are medium-sized and well filled out. Long harvest period until the end of the season.

#### *3.1.4 'Palieri'*

The bunches are long, medium full and have an average weight of 600 g. The berries are large (17–20 mm) and oval, with a medium-thick, firm skin covered with pruin, and the pulp is crunchy, resistant, juicy, and medium sweet (14°- 16°Brix). Preliminary results for 'Palieri' grapes from the south of Portugal have 15°Brix, an acidity of 0.20 g/100 g−1 fresh weight, and an SSC/TA ratio of 40 [27]. 'Palieri' grapes are resistant to handling and transport due to high coefficients of apparent elasticity and firmness of the flesh. Moreover, berries are characterized by their high resistance to compression and a low resistance to rupture [27].

### *3.1.5 'Dona Maria'*

'Dona Maria' is a Portuguese variety obtained in the 1950's in the *National Agricultural Station* in Oeiras, Portugal, and quickly spread throughout the country. It is a cross of 'Moscatel de Setubal' and 'Rosaky', their brunches are large or very large, cylindrical, rarely winged. The berries are very large, elliptical in shape, with a yellowish green color when ripe [28]. The skin is resistant, covered with a thick layer of pruin, and the pulp firm and succulent. It is much appreciated for its floral flavor, and very sweet and large berries. The bunch ripens in August and at the first fortnight of September coinciding with many other varieties [28]. Nevertheless, 'Dona Maria' grapes have a great commercial interest in Portugal, due to its light muscatel flavor and sweetness. Moreover, it is practically only sold in local markets. Berries are resistant to transport and keep their fresh appearance for a long period, if cold storage is done correctly, otherwise the berries of yellowish-green color turn brown [28]. The worst defect of 'Dona Maria' is the fact that the berries detach easily from the pedicels in an advanced period of maturation. If this problem is fixed, considering their exquisite flavor and long shelf-life, it could be considered a variety with potential for a wider market.

### **3.2 Seedless varieties**

The cultivation and consumption of seedless table grape cultivars has increased considerably in recent years, by demand of the consumer who highly appreciates the absence of seeds and is willing to pay more for these sweet, firm and seedless grapes [17]. In fact, one of the objectives of the current breeding programs is to obtain varieties with good characteristics and mandatorily seedless [23]. 'Thompson Seedless' is the main source of seedlessness for breeding programs around the world, while also being an important commercial seedless variety for consumption [26].

According to FAO and OIV [29], the criteria to select the new varieties, among other, are: the presence or absence of seeds, shape, color, skin thickness, maturity period, resistance against diseases and pests, capacity to be transported without damage and shelf-life.

Although it seems impossible to list the current commercialized varieties of table grapes, a summary description of those considered to be the most significant, taking into account the following criteria: the varieties with commercial/economic

importance, worldwide; the varieties that are very innovative and those that, in our opinion, will be prominent in the future.

According to Fortes and Pais [30], the traditional varieties of *Vitis vinifera* table grapes are: 'Alphonse Lavallée', 'Bastardo Ruzo', 'Dominga', 'Moscatel Negro', 'Muscat of Alexandria', 'Ribier', 'Thompson Seedless'/'Sultanina', 'Tinta Pais'. The modern varieties are 'Autumn Royal', 'BRS Morena', 'Cardinal', 'Crimson Seedless', 'Flame Seedless', 'Guibao', 'Italia', 'Michele Palieri', 'Moscatel Italica', 'Muscadoule', 'Muscat Hamburg', 'Napoleon', 'Otilia', 'Perlon', 'Red Globe', 'Superior Seedless' [30]. Moreover, some table grape varieties resulting from traditional and modern interspecific crossing or other species of *Vitis* have been described, namely: 'Alachua', 'BRS Clara', 'Campbell Early', 'Canadice', 'Delaware', 'Eudora', 'Flouxa', 'Honey Seedless', 'Janet', 'Kyoho', 'Nativa', 'Niagara', 'Ruby Seedless', 'Southland', 'Tamnara', 'Tano Red', 'Concord' and 'Muscat Bailey A' [30].

Recently, a group of researchers from the *Universidade de Évora-MED*, Portugal, in collaboration with a company from the nearby region, proceeded to characterize some apyrenic varieties ('Timco', 'Melody', 'Scarlota' (Sugra19), 'Alisson', 'Melissa' and 'Autumn Royal') produced under the specific climatic and agronomic conditions of a producer company located in Alentejo, South of Portugal (38°05′22.2"N 8°04′51.1"W). The obtained results are generally in agreement with those published worldwide, although with increased soluble solids content (SSC) values. Timco', 'Scarlota' and 'Alisson' table grapes had the heavier berries. 'Melody', 'Melissa' and 'Autumn Royal' were lighter (p < 0.05). Although 'Melissa' had the lightest berries, their caliber was higher than most. 'Alisson' has the smallest caliber berries. 'Melissa' had the lower skin firmness of all the varieties studied. There are no statistically significant differences in SCC and their values were all very high. 'Autumn Royal' had the lower acidity of all varieties studied while 'Scarlota' had the highest (p < 0.05). Total phenolic content was higher in 'Autumn Royal' and lower on 'Timco' (p < 0.05). 'Autumn Royal' showed the higher capacity of scavenging free radicals (p < 0.05). Considering all the results presented and the current interests of consumers, 'Autumn Royal' can be pointed out as a very interesting variety from the organoleptic and nutritional point of view. To perform shelf-life tests with this variety produced in this edaphoclimatic conditions is necessary to define an adequate marketing strategy [31].

#### *3.2.1 'Sultanina' or 'Thompson seedless'*

'Sultanina' is the first apyrenic or seedless variety cultivated in the world. The synonyms for 'Sultanina' are numerous: 'Kishmish' in Afghanistan, 'Thompson Seedless', 'Sultana', or 'White Sultana', 'Kišmiš', among others [11]. It is an ancient grape variety, originating from Afghanistan. This variety has a multiple purpose use, for drying to produce raisins, for vinification to produce wine especially in Turkey and the USA, distilled to make a spirit beverage (Raki, a typical Turkish beverage obtained by distilling fresh or dried grapes, flavored with aniseed and with an alcohol content of 45%) and also for fresh consumption [11, 32]. 'Sultanina' grapes are highly valued by customers as table grapes due to their organoleptic quality characteristics, mainly sweetness, sharpness, firmness, and light green brilliant color. The berries are seedless, elliptical, of small to medium size, 16–22 mm, and cylindrical in shape, yellowish green. Their flavor is said to be sharp, sweet (17°-19°Brix), juicy and the pulp crisp and consistent. The bunches are large, cylindrical, or conical and compact, with a very variable weight depending on cultivation practices, between 350 g and 700 g. Their small caliber can be improved trough applications of gibberellic acid. Maturation is somewhat late.

#### *Table Grapes: There Is More to Vitiviniculture than Wine… DOI: http://dx.doi.org/10.5772/intechopen.99986*

According to OIV [11], this variety is the leading variety of table and raisin grapes in the world, with about 273,000 hectares, however, the OIV estimates a decrease of vineyards. It is particularly cultivated in Middle Eastern countries and Central Asia. As extreme production values we can refer to 80 tons/hectare in South Africa [11]. This is one of the most economically important fruit crops worldwide [33, 34].
